System for reducing sulphur dioxide to sulphur by natural gas



Jan. 20, 1942. FLEMMG l L 2,270,427

SYSTEM FOR REDUCING SULPHUR DIOXIDE 'I'O'SULPHUR BY NATURAL GAS Fil'ed Aug. 15, 1939 INVENT RS Eda/aid BY]: L'leon Fifi PatentedlJan.20,1942' IYSTEM FOR REDUOIN SULPHUR DIOXID TO SULPHUR BY NATURAL GAS Edward P. Fleming ana 'r; Clean Fitt, Salt In.

City, Utah, assignors to American smelting and Refining Company, New York N. Y., a comration of New Jersey Application August 15, 1939,1Serial No. 290,152

2 Claims.

This invention relates to the production of sulphur from gases comprising sulphur dioxide, such as those obtained in various metallurgical operations, employing natural gas as the reducing agent;

Itis an object of the invention to provide a system that is economical in operation and capable of obtaining a high percentage of conversion Ioi the sulphur content of the gases to elemental orm.

Other objects and advantages will be apparent irom the following description taken in conjunction with the accompanying drawing which is a diagrammatic section through a typical plant embodying the system of the invention.

Referring more particularly'to the drawing,

It indicates a reduction furnace provided with inlet l4. The furnace I is provided with an outlet l6 which leads through heat exchanger l8 to a first catalyst chamber 20. The outlet 22 from the catalyst chamber branches into pipes 24, 25 and 28 which are provided with valves 30. 32 and 34, respectively. Pipe 24 leads to cooler 35 which is in turn connected with a first precipitation unit 28 by pipe 4ll.- The pipes 25 and ansulphur dioxide inlet i2 and a natural gas in theneighborhood of .130Q:C., the reduction reaction products passing from the chamber l0 through the heat exchanger l8 into the first catalyst chamber -20: V

This first catalyst chamber contains .diatoma ceous earthor diaspore and is operated-at a temperature of notless than ,450" C. and preferably not over 600 C. to-efiect conversion of any car bonyl sulphide to elemental sulphur vapor 101+,

lowing which the sulphur vapors and other gases 7 including hydrogen sulphide are delivered through pipes 22, 24 to cooler 36 and thence to electrostatic precipitator 28 which is operated in the neighborhood of 1s0" c.

From the precipitator 38 the relatively sulphurfree gases pass through pipes 52, 54 into heat exchanger 42 and thence into the secondcatalyst chamber 66 which like chamber 20 contains a suitable catalyst but is operated at a temperature below the dew point of sulphur vapor at the partial pressure employed and in which the hy-- drogen sulphide'is converted to elemental sul- 28 lead, respectively, to a pair of identical heat exchangers 42, 44 and thence through pipe 46 to cooler 38 via pipes 48 and 50, respectively; Outlet 52 of the first precipitatingunlt 38 branches into pipes 54 and provided with valves 58 and 80, respectively. The said pipes 54, lead through the heat exchangers 42, 44-through pipes 62, i4

into-a pair of second catalyst chambers 66, I8,

respectively, which, like heat exchangers 42, 44 are mounted in parallel. Outlet pipes ll, 12

from the catalyst chambers connect with the main outlet pipe I4 which enters a second cooler II, which cooler is connected to a second precipitation unit I8 by pipe 80. All units in the system, beginning with the cooler 20 and endin with the final precipitation unit I8, are provided with conventional clean-outs or drains, not.

shown.- In one manner of operation, the gases comprising sulphur dioxide and a properamount 0! air orjother combustion-supporting gas, are pre-. heated by passing through the heat exchanger "and thence introduced into the reduction furnace l0 through pipe l2. The correct prophur. In time the accumulation of sulphur in the chamber 66 will cause back pressure to develop in the system at which time valve 32 is opened topermit a sufilcient quantityof hot gas from chamber 21f to pass through exchanger-42 to chamber 66 from exchanger 42 above the dew point thereby carrying the sulphur out of chamber 66 through pipe I4 into electrostatic precipitator". The gases entering exchanger 42' through pipe 26 after giving up the'requlsite heat therein are conducted through pipe 46 to cooler 36. r

While valve 32 is in its most open position for clearing chamber 65 as aforesaid, chamber 68 is operating below the'dew point on gases supplied by line 64 from precipitator 38 through pipes I2, 56 andeichanger 44. When sufflcient.

back pressure develops in catalyst chamber 68, it is cleared by opening. valve 34 thereby supply- .ingsuificient hotgas to exchanger 44 to raise the gases sweeping chamber 68 above the dew point. 7 Chamber 66 having meanwhile been cleared, the opening of'valve 32 is reduced to portion or natural gas is introduced into the reeduction chamber =|I along with the sulphur dioxide bearing gases through pipe 4. Reduction is effected in the chamber It at a temperature substantiallyno less than 1250 C. and preferably again put chamber 66 into operationbelow the dew point.

It will be observed that in bulk of the sulphur vapo irom the reduction furnace and from the st catalyst chamber wherein carbonyl sulphide 'is converted to sulphur, are removed prior t'oxthe entrance of the raise the/temperature oi the gases entering the system above I described, a plurality of sulphur precipitating units are provided so that in peration the great gases into the catalyst chambers wherein conversion of the hydrogen sulphide is eilected.

Further, the provision of heat exchangers 42, i l

and catalyst chambers 66, 68, both in parallel, lends great flexibility of operation to the system.

The operation or the system as above described is highly efilcient in conversion of sulphur dioxide to elemental sulphur both on relatively lean and richer gases. However, it will be understood that various modifications, substitutions their entrance into said second catalyst chamhere by heat exchange with hot gases from said first catalyst chamber, and means for returning said last mentioned gases to said first precipitating unit. 7

2. A system for reducing sulphur dioxide with natural gas comprising a reduction furnace, a first catalyst chamber receiving the gases from the reduction furnace, a first sulphur precipitatand additions may be made by those skilled in the art to adapt the invention to'varying conditions and uses within the scope of the invention.

What is claimed is: 1. A system for reducing sulphur dioxide with natural gas comprising a reduction furnace, a first catalyst chamber to which the gases pass from the reduction chamber, a first sulphur precipitating unit, a pair of second catalyst cham here in parallel, conduits and control valves for supplying gases from the first catalyst chamber to the first precipitating unit and thence to said second catalyst chambers, a final sulphur precipitating unit to which gases are passed from said second catalyst chambers, means for heating gases from the first precipitating unit prior to ing unit, a plurality of second catalyst chambers in parallel, conduits and control valves for supplying gases from said first catalyst chamber to the first precipitating unit and thence to said the first precipitating unit via the cooler preceding same.

EDWARD P. FLEMING. T. CLEON FITT. 

